events/2006-03-21-mix06-microformats

Microformats discussions at Mix06

March 21st, 2006

Lessons from the Trenches

"Lessons from the Trenches: Engineering Great AJAX Experiences"

11am-12:15pm

Presenter: Scott Isaacs

Slides: PowerPoint Document

Notes/Quotes:

• taken by Tantek Çelik live at the event into #mix06 on irc.freenode.net
• cleaned up and archived here by Dimitri Glazkov

Modern Development Patterns

• Apply OO principles to web development
• Shared methodology with Atlas
• Namespaces, Encapsulation, Inheritance, Object Lifecycle
• Separate semantics, presentation, and behavior

Live Clipboard Demo

• "microformats are another key aspect of Web 2.0"*
• hCard for contacts, start with class="vcard"
• similarly use hCalendar for events
• what Live Clipboard is a use of microformats for integrating your data
• (starts demo)
• starting with just the microformat -- "key part of the ecosystem for remixing the Web"
• "I can basically say anything on the page that has class name vcard, I'm going to bind one of those Live Clipboard container objects to it"
• "then I'm going to specify the resources to bind to it, ex: clipControl.js and .css"
• dynamic recognition of microformats on the page
• "any microformat on the page, I want to make copyable"
  • "I wanted to copy the hCalendar"
  • "I copied it from IE"
  • "I went to Firefox"
  • "and I pasted"
  • "and the event item shows up on a page viewed in Firefox"
  • "I can copy and paste this whereever I want"
  • "I can copy and paste from Eventful"
  • "I can do the same thing with other microformats on the page"
  • "I can copy a contact from the IE page ?and paste into that same page that I pasted the event"
• "all the contacts in Hotmail will be hCard automatically remixable into the rest of the Web"
• if you start building gadgets with microformats, we'll make them automatically remixable with other gadgets
• start exploring using microformats in your web pages
• we can start establishing an ecosystem of relevant data

Web Service Integration

• Do not want to continually parse XML
• we don't want to deal with SOAP envelopes on the client
• instead, we build javascript proxies
• Desire a more natural and efficient approach
• Web Services generate JavaScript proxies: WeatherService.requestWeatherReport(strLocation,onReceipt)
• Use generic format for transport (e.g., JSON)
• Incoming requests marshaled to native server format and outgoing responses to client format
• Use xmlHttpRequest to access the network, but the wire format is transparent to the application
• Use raw XML for "documents" (e.g. RSS)
• but parsing a several 100k document will take upwards of 400ms
• and that is too long
• user thinks browser has locked up
• explore other approaches such as JSON to gain the most efficiences

efficiency

Optimizing the Network

• AJAX-style applications can become very chatty

...

Be Wary Of Security

• "could probably spend an hour on this one slide, but will try not to"
• XSS is an industry challenge we all need to address more
• as you start exposing services at the edge, XSS becomes a much bigger deal
• e.g. Gmail, within 3 days, coders developed an API to use Gmail as a disk store
• Define a standard UI feedback metaphor and stick to it
• (missed slide)

Prioritizing Network Requests

• AJAX Scenario
• Your page is preloading images
• User clicks "Buy It" from ...

Code/Resource Deveployment

• More Interactivity = More Code = Slower Site (script are executed synchronously serially)
• How do you build sites with lots of componenets
• How do you build a "portal" where the user controls the scope of the application
• How do you efficiently deploy the necessary code and resources?
• Understand how the browser works
• Scripts included on the page block and load one at a time
• Large number of script blocks can greatly stall loading
• System for deploying code
• Patterns allow component resources to load in any order
• Deployed code asynchronously leveraging all available connections
• Prioritize the loading of components
• Never expire static content (change the URL to break the cache)

X-Browser Development

• Minimize browser specific code in the business logic
• Abstract and centralize API differences
• We extend Firefox and Opera DOM to be compatible with IE
• CSS Differences - Avoid Hacks
• We classify and override via standard selectors
• HTML class="Mozilla M1 D5 Windows"
• Body {margin:10px}
• .Mozilla Body {margin:5px} /* Override Mozilla */
• (hmm... this is quite clever and much more readable)
• ... missed slide ...
• demo of Scott's blog

Back Button And Addressability

• Users expect the web to work (I love that line)
• Demo: MSN Spaces, Windows Live
• Travelog (History stack) is hard
• Windows Live beta
• back button works
• you can change the hash of the URL [fragment identifier] without reloading the URL
• and thus keep back button working

Accessibiliy

• Web Accessibility is challenging
• "Use HTML semantics appropriately"
• (wow how far semantic HTML awareness has come in the past four years)
• HTML Accessibility
• Always use structural semantics to establish "role"
• E.g., Hn, Label, TH (table headers), lists, etc.
• (rather than nested DIVs)

Building Web Applications

...

Q&A

• Q: What kills JavaScript perf is memory leaks in the browser
• IE6 has some leaks
• if you create a circular reference between a document object and a javascript object then it won't go away

• Q: mashups with SSL
• A: interesting challenge. the real question is how do we securely integrate in a way that is trusted by partners and customers? you have to go entirely HTTPS across the board

• Q: are you familiar with the DOJO toolkit? it solves a lot of the problems memory leaks, back button
• A: haven't looked too deeply at DOJO. we have a system where objects get created and destroyed all the time. not sure if they do document level garbage collection or what.

• Q: about Atlas
• A: ...

• Q: about using AJAX to build a 24fps videogame
• A: (heh)

• Q: is there someway we could have a simple lean AJAX request?
• A: ...

• Q: what is wrong with using iframes?
• A: 1. themes won't work with the iframe this is ASP.NET-specific reference --DimitriGlazkov
• A: 2. iframes consume a lot of memory (read: Trident instance) on the order of 20 megabytes of memory (YIKES!)
• A: 3. security